1. Field of the Invention
The present invention relates in general to electrical power supplies, and in particular to power supplies for providing a d.c. voltage in response to static electric fields.
2. Description of the Prior Art
Electrets are substances which typically have high dielectric constants. Electrets are herein defined as those materials which, in response to exposure to an electric field, will emit a voltage for extended periods of time after the electric field has been removed. In some cases, these extended periods of time may last as long as several months, or even for several years. Electrets include materials such as wax and barium titanate. A representative list of electret materials is set forth below in Table I, in the section entitled "Detailed Description of the Preferred Embodiment."
Some of the first experiments with electret materials were conducted as early as 1925, using wax as the electret material. Later experiments gradually expanded to titanate series of substances, as reported by Russian investigators in the 1960's. In these experiments, electret materials were exposed to strong electric fields for periods of time. Then, the strong electric fields would be removed and the electrets would continue to emit voltages for long periods of time after the strong electric fields were removed. The emitted voltage potential would quickly deteriorate to very low voltage levels after the strong electric fields were removed. The electret material would often continue to emit these low voltage levels for months, and in some cases, even for years after the strong electric fields were removed. However, the low voltages emitted by the electret materials in these experiments, although present for long periods of time, were too small to provide a useful source of electric power.
Further, static electricity has also long been known in the art. The buildup of static charges have often resulted in static electric fields having very high voltage potentials. These high potential static electric fields have remained largely unusable as a source of electric power, that is, for providing power to operate electric devices.